Pulverizing mill and the like



March l5, 1932. E wL GREEN ET AL PULVERIZING'MILL AND THE LIKE FiledMarch 13, 193()A r2 Sheets-Sheet Ercan @gorge Tod/'Gm UNHIUVIK 72 LMarch 15, 1932.

E. w. GREEN ET AI.

PULVERIZING MILL AND THE LIKE Filed March l5, '1930 2 Sheets-Sheet 2fia/ward Wfl/mm 67rd en.

Patented Mar. 15, 1932- UNlTl-:D STATES PATENT OFFICE EDWAED WILLIAMGREEN, or LONDON, AND eEoneE EoDm- UNrrnnNx, or' NEW SOUTHGATE, LONDON,ENGLAND, ASSIGNORS LIMITED, OF ENGLAND rULvEarzINe MILL AND THE LIKEApplication led March 13, 1930, Serial No. 435,406, and in Great BritainMarch 14, 1929.

This invention relates to improvements in` pulverizing mills and thelike in which pulverizatiqn is elected by a plurality of ballscooperating with tracks. v

5, The invention has for one of its objects the provision of meanswhereby more effective and regular grinding can be performed than ispossible with known arrangements.

Another object of the invention is the provision of means whereby moreeffective discharge of pulverized material from the balls is obtainedthereby enabling a pulverizing mill of higher duty to be produced thanhas been possible in the past.

Another object of the invention is the provision of means whereby' moreeifective air currents are produced for conveying the pulverizedmaterial `delivered from vthe rotary track to the delivery orificethereby enabling more efficient operation to be obtained.

A further objectv of the invention is an im'- proved constructionparticularly'adapted for the reduction of crushed coal into a powder ofthe neness which is necessary when coal is to be consumed in pulver'izedform.

A further object of the invention being the provision of means wherebythe pulverized material delivered from the apparatus is more uniformlygraded than has been usual with apparatus of this type.

The invention consists in the arrangement of a plurality of balls in arotating track, said balls being maintained therein by an elasticallyloaded nonrotary track; means for feeding crushed material to saidrotating A track to be pulverized; means for producing an annular streamof air for entraining the^ material delivered fr0m` said track, saidstreamfof air conveying particles of the pul- *0 verizedmaterial of lessthan a predetermined l mass to and through'a delivery passage whilst theheavier particles are returned by the force of gravity to the rotatingtrack for further pulverization.

In the drawings Figure 1 illustrates in Sec# tional elevation one formof improved mill ,l constructed in accordance with this invention; p l

Figure 2 is a plan view inssection taken o n the line/2 2 of Figure 1;

material from the bevelled edge toI the delivl ery assage.

Als) illustrated part of this vertical sha a supported upon a suitableballv thrust b and provided with worm and in 'the drawings forming vwormwheel gearing o to enable rotation of the shaft a to be effectedalthough other ,T0 R. & H. GREEN' .AND SILLEY' WEZIIB4 sfpecificationthe mill comprises a l means of rotation may be employed if so desired.'The vertical shaft a is provided with a journal d at its upper endadapted.

to rotate in a bearing e formed'inlthe Iupper partof the stationarystructure f of themaf chine which also comprises va supply passage g forthe admission of roughly crushedmaterial., a delivery passage h for thepulver` ized material and an air inlet orair inlets c'.

The roughly crushed material is supplied to the hopper k and is fedjbytheJ screw conveyor l throughthe tunnel m to the orice g,

the conveyor Z being'rotated at the required f speed by means of thebevel wheels an. shaft o, crank p, lever q, pawl 1' and ratchet wheelra, such means being provided'to prevent the admission of air' throughthe'hopper le as may be necessary. i

Beneath vthe supply passage g a stationary circular serrated element t'is located, the shaft a having feeder arms u and a conical toothedbraker v at this point so that the material is forced by the feeder armsu between the4 serrations on the stationary element t and the teeth ofthe braker v means adapted to'be shearedy being provided, if necessary,should excessive torque be required from the shaft a.v

The material delivered from the serrated element t is discharged on to atrack w mounted on and rotated by the vertical shafta. l A A A pluralityof balls a: of suitable diameter are arrangedon the track w andmaintained .in position by a nonrotating ring element 'y suitably loadedby springs a or the like, the

number of balls a: provided being insufficient to lill the track wcompletely so that a gap w1, see Fig. 2, exists between contiguous ballsat one point. The dimension of the gap m1 depends upon a number ofconditions but in a general way when the track w is suiiciently long toaccommodate a given number of balls a single ball may be omitted. Theconfiguration of a transverse section of the track w is such that theballs as engage therewith on a line extending substantially from avertical plane to a horizontal plane said track lw being continuedupwards at its larger diameter so as to form a bevelled edge` or fencew1. In transverse section the configuration of the bevelled edge orfence w1 is a portion of a paraboloid lying between two horizontalplanes or approximates to such curve, the contour being so proportionedthat the fuel whether ground or not is just able `to run up saidbevelled edge w1 by centrifugal force.

In proximity with the bevelled edge rw1 and exteriorly thereof astationary circular lipv wz is arranged, the lip fm2 cooperating with anadjustable sleeve w3 mounted on the cover f1 of the stationary structuref so as to form an annular jet supplied with air from the air inlet z',the sleeve 'w3 being raised or lowered by means of the finger operablenuts @v4 which cooperate with the screwed stems w5 attached to saidsleeve.

Owing to the location of the air inlets z' i the direction of fiowof theair to the annular jet is fixed, the velocity and quantity of said airbeing independently controllable by varying either the area of the jetby raising or lowering the sleeve w3 or by varying the speed of the fanexhausting air from the separator the base of which is indicated by theletter S in Figures 1 and 2.

In operation crushed material, for eX- ample, coal, is fed by theconveyor Z through the supply passage g to the track w. As previouslystated the track 'w is rotated at such a speed that the material underthe action of centrifugal force can just pass up the bevelled edge w1.During the passage of the coal across the track 'w it is pulverized bythe balls and the delivery from the edge w1 is entrained by the streamof air issuing from theannular nozzle formed by the lip wz and thesleeve w3 and carried in the direction of the arrow 3 between the backof the ring element y and the inside surface of the cover f to thedelivery passage h particles having less than a predetermined mass beingconveyed throughthe passage h to the separator whilst particles ofgreater -mass fall, as indicated by the arrow 4, under the action ofgravity, and intermingle with the feed from the passage g, asdiagrammatically illustrated in Figure 4E.

When coal is being pulverized in such an apparatusthe air supplied tothe inlet mav be heated as desired in which case the air inlets i orsome of them may be closed with suitable doors the heated airbeingsupplied loaded non-rotary track, a series of balls dis-v posed betweenand travelling round said tracks, an annular suction passage round saidtracks communicating with the external atmosphere, a beveled edge on thedischarge periphery of the rotating track of the form of aparaboloidlying betweentwo horizontal planes, a stationary circular lip inproximity with the said beveled edge and an adjustable sleeve sliding onthe upper part of the mill and having an outwardly and downwardlyprojecting lip arranged to direct the suction air to meet the stream ofpulverized material l thrown'out centrifugally and direct thecombinedstream in an upward and inwarddirection so that the heavierparticles of solid material are returned by gravity to the inside Vofthe said tracks for re-pulverizing.

2. In an improved mill as claimed in claim 1, a stationary serrated ringmounted in the supply passage of the mill, a rotating serrated elementcarried by ythe rotating track, and

yrotating feeder arms in the said supply passage adapted to crush thematerial supplied immediately before saidmaterial is applied to saidrotating track for pulverization.

3. In an improved mill as claimed in claim 1, the arrangement of theballs between the two said tracks so that the aggregateof the,

